The Georgia father charged with murder for leaving his 22-month-old son in a hot car told police that he had done online research about child deaths in vehicles and “what temperature it needs to be,” according to warrants released Saturday.

The father, Justin Ross Harris, remained locked up in suburban Atlanta while the family gathered in Alabama later Saturday to mourn the child, Cooper. He died June 19 in a manner that the medical examiner said was “consistent with hyperthermia.” According to the warrants, “Justin stated that he was fearful that this could happen.” The warrants do not spell out when Harris conducted the research. Harris has pleaded not guilty, and his lawyer has declined comment to NBC News.